EP1940665A1

EP1940665A1 - Adaptive cruise control featuring recognition of a traffic jam

Info

Publication number: EP1940665A1
Application number: EP06793265A
Authority: EP
Inventors: Juergen Boecker; Dieter Hoetzer
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2005-10-20
Filing date: 2006-09-06
Publication date: 2008-07-09
Anticipated expiration: 2026-09-06
Also published as: DE502006004030D1; US8229644B2; EP1940665B1; JP2009511357A; US20090299598A1; DE102005050277A1; WO2007045523A1

Abstract

Disclosed is an adaptive cruise control for motor vehicles, comprising a sensor system (12) for locating preceding vehicles and a controller (20) which regulates the speed of the vehicle and/or the distance to a preceding vehicle based on predefined control parameters. Said adaptive cruise control is characterized by a traffic jam recognizing device (28) and a setting device (30) for adjusting the control parameters to a recognized traffic jam situation. Starting indications can be cancelled and particularly the setpoint acceleration of the vehicle can be reduced when a traffic jam unlike a red light, for example has been recognized.

Description

description

title

Distance and speed controller with jam detection

State of the art

The invention relates to a distance and speed controller for motor vehicles, comprising a sensor system for locating vehicles in front and a controller which regulates the speed of the vehicle and / or the distance to a vehicle in front on the basis of predetermined control parameters.

Such distance and speed controllers are also referred to as ACC systems (Adaptive Cruise Control) and as a sensor system typically have a radar sensor with which the distances and relative speeds of preceding vehicles can be measured. In this way it is possible to track an immediately preceding vehicle, the so-called target object, at a suitable distance or, more precisely, with a suitably selected time gap. In free-ride mode, if no target object is present, a control to a target speed, the z. B. is given by a desired speed selected by the driver.

Examples of predetermined control parameters are the setpoint speed and the "dynamics", the z. B. is characterized by the allowed in normal operation limits for the amount of vehicle acceleration and deceleration.

The previously used ACC systems are generally open for trips

Motorways or well-developed country roads provided and can be activated only above a certain minimum speed, for example, 30 km / h.

However, there are ACC systems with an extended range of functions under development that offer, for example, the following additional functions: follow-up drive at very low speeds (below 30 km / h), braking in the state when the vehicle in front stops, automatic stopping of the vehicle in the state and optionally automatic restarting, if traffic permits. The starting process may then be preceded by an acoustic starting instruction for the driver. This extended functionality is often referred to collectively as a stop-and-go feature.

To improve the traffic flow telematics systems are known with which traffic congestion in the route network can be automatically detected and reported to a traffic center. In DE 199 17 154, DE 101 26 872 and DE 196 06 258 congestion detection systems are described in this context, which aboard

Vehicles of a so-called sampling fleet are installed and are able to detect a traffic jam situation based on the speed profile of their own vehicle. According to DE 196 06 258, the speed of the vehicle is detected continuously for this purpose and classified according to predetermined speed classes. The classification result is then subjected to a temporal integration process, and from the integration result, a probability value for the presence of a congestion situation is calculated with the aid of fuzzy logic.

Advantages of the invention

The invention with the features specified in claim 1 makes it possible to automatically detect a congestion situation in the context of the distance and speed control and then automatically adjust the control parameters to the specific conditions of such a congestion situation.

In particular, the invention makes it possible to perform a control based on a reduced dynamics in the dust operation, so that start-up, acceleration and braking operations in the dust operation with reduced dynamics, resulting in a quieter and more fuel-efficient driving.

If the control functions are available not only on crossroads, but also on rural roads or in city traffic, the system should also be able to differentiate between a "real" traffic jam situation and other traffic situations in which it also temporarily leads to a journey very low speed or may come to a stop, such as at a stop in front of you red traffic light. While in a traffic jam low dynamics is advantageous, namely when starting in a traffic light queue on the contrary should be done in a scheme with a high dynamic, so that during a green phase, the highest possible number of vehicles can pass the intersection. The automatic congestion detection can be achieved according to the invention in any situation an adapted system behavior.

Advantageous embodiments and modifications of the invention will become apparent from the dependent claims.

The jam detection is preferably based on an evaluation of the locating signals of the

Sensor system, so for example the radar sensor, in combination with an analysis of the speed traveled in the recent past. As characteristic of a traffic jam is considered that a preceding vehicle is tracked, so the radar sensor has detected a target object, and that the speed traveled for a long time within a certain speed range with lower

Average speed remains.

In a particularly preferred embodiment, the difference between a predetermined limit speed and the current driving speed over time is integrated to calculate a congestion probability.

The longer the speed traveled remains below the limit speed, the greater the probability of congestion. When the limit speed is exceeded, the congestion probability does not abruptly decrease to zero, but decreases only gradually, corresponding to the decrease of the time integral of the speed difference. This ensures that a brief "intermediate spurt" as it occasionally occurs in congestion situations is not mistakenly interpreted as a resolution of the congestion.

Preferably, the integration of the time difference is suspended when the speed traveled decreases below a lower limit speed. This prevents that a temporary standstill of the vehicle, for example in front of a traffic light, leads to a further increase of the integral and is then wrongly interpreted as a congestion situation. - A -

Preferably, the integration is also suspended when the integral has reached a certain maximum value. This prevents the integral from assuming extremely high values in the event of a prolonged jam, which would have the undesirable consequence that the resolution of a jam would only be recognized late, namely only when the integral returns from the very high value to a low value has decreased.

In order to enable congestion detection in the sense of a yes / no statement, the congestion probability determined by integration can be compared with an upper and a lower threshold value. If the upper threshold value is exceeded, the jam signal assumes the value "yes" and falls below the lower threshold

Threshold, it returns to the value "no". The upper threshold may be identical to the maximum value at which the integration is suspended. In addition, the control signal assumes the value "no" and the integral is reset to zero if the radar sensor no longer locates a vehicle ahead.

An appropriate value for the upper limit velocity needed to calculate the integral may be determined empirically in advance. Preferably, this value depends on the detected road type, so that it is higher, for example, on highways than in city traffic. To detect the road type is a connection of the distance and speed controller to an optionally present in the vehicle

Navigation system appropriate.

Likewise, the height of the upper limit speed may also be dependent on the number of lanes and on which lane the own vehicle is located. For example, the upper limit speed on the left lane could be higher than on the right lane.

The lower limit speed may also be road type and / or lane dependent and may be defined, for example, as a certain percentage of the upper limit speed. The road type and / or lane may alternatively or additionally also be included in the determination of the thresholds with which the integral is compared.

In the event of a congestion, it is preferable to adapt the control parameters which determine the starting and / or braking dynamics of the vehicle, so that in congestion situations more emphasis is placed on comfort than on dynamics, while on the other hand, for example, in a starting situation in front of a traffic light, more emphasis is placed on greater dynamics.

In front of a traffic light system, the boundaries between a starting situation and a

Jam be fluent, for example, when the queue of vehicles in front of the traffic light is so long that the traffic light junction can be passed only after several green phases. Typically, in such a situation, the differences between the red and green phases become more and more blurred as the distance to the traffic lights increases, ie at the end of the queue there is a congestion-like situation with stagnant traffic, while with increasing approach to the traffic light intersection an increasingly clear change between standstill phases and relatively high-speed phases. With a suitable choice of the limit speed, the system will behave so that when approaching the traffic light intersection is automatically switching from dust operation to appropriate for a starting situation in front of a traffic light higher dynamics.

Known controllers with stop & go function are often designed so that after a vehicle standstill, at least when this stoppage has taken a certain amount of time, the driver receives an audible, visual or haptic Anfahrhinweis before the automatic starting process (possibly even after Acknowledgment by the driver) is initiated. In congestion situations, however, the frequent issue of such Anfahrhinweise is often perceived as disturbing. A suitable adaptation to the detected traffic jam situation can therefore also consist in the fact that, when the traffic jam is detected, the output of the starting signal is suppressed before the automatic starting process is initiated.

According to one embodiment of the invention, it is also conceivable that when detected congestion, the target speed corresponding to the desired speed selected by the driver before driving on the tail end, is reduced to a lower value, so that the vehicle, at least after a long stagnation period, not automatically accelerates back to the previously set speed, but first waiting for a renewed confirmation (increase in the desired speed) by the driver. Finally, the inventively provided device for congestion detection can also be used for other vehicle systems, for example, to automatically send a traffic jam message to a traffic center, for a command to the navigation system to calculate a detour route, or for a command to the electronic control of the automatic transmission adapt the shift program of the gearbox to the traffic jam situation.

drawing

An embodiment of the invention is illustrated in the drawing and explained in more detail in the following description.

Show it:

Figure 1 is a block diagram of a distance and speed controller; and

Figure 2 is a timing diagram of various signals in a device for congestion detection.

Description of the embodiment

In Figure 1, an ACC system 10 is shown with Stop & Go function, the basic structure and operation of which can be assumed to be known and therefore only briefly outlined here.

An angle-resolving radar sensor 12 installed in the vehicle provides location data (distances, relative speeds and azimuth angles) of the located objects to the ACC system 10. The measurement data is updated cyclically. In a tracking module 14, the current measurement data are compared with the measurement data from previous measurement cycles, so that the movements of the individual objects can be tracked.

A (not shown) Kurprädiktionsmodul used to estimate the probable course of the own vehicle, z. B. based on the road curvature in the just passed through the road section. On the basis of the predicted course becomes one Driving tube determines within which those vehicles must be located, which come as a target for the distance control in question.

However, since the tracking module 14 is also capable of recognizing outdated or overhauled vehicles on side lanes, information about how many lanes the currently traveled directional lane has and in which lanes the own vehicle is located can be obtained in a lane detection module 16 ,

In a plausibility module 18, the located and tracked in the tracking module 14 objects are plausibility, d. h., for each object a probability is given that it is inside the raceway. In this case, it is taken into account that the location data, in particular the transverse position data, have certain error tolerances which increase with increasing object distance. If the probability that the object is within the travel tube is above a certain threshold, the object is "plausibility", i. that is, it is treated as a relevant object that is in its own lane. Finally, among the objects that are so plausible, the one with the smallest distance is finally selected as the target object for the distance control.

In a controller 20 takes place on the basis of the location data of the target object, the actual distance control by engaging in the drive system and, if necessary, the braking system of the vehicle so that the target object is tracked with a selectable by the driver within certain limits time gap. If there is no target object, the system is in free-ride mode and control is performed on one of the

Driver selected desired speed.

The ACC system 10 described here has an interface to a navigation system 22 of the vehicle. This navigation system contains a road map stored in digital form and determined using a GPS system

(Global Positioning System) the current position of the own vehicle, so that in a classification module 24 of the ACC system also information about the type of road (highway or highway) and about upcoming exits, intersections, junctions, and the like are available. In addition, based on the data provided by the navigation system, it is also possible to decide in which national territory the vehicle is located and whether the preceding lane section is a highway outside built-up areas or an inner-city street, so that information about the applicable statutory speed limits can be provided.

The data of the classification module 24 and of the lane recognition module 16 are fed to a jam recognition device 28 together with the current travel speed V of the vehicle measured by a speed sensor 26. In addition, the jam recognition device 28 receives from the plausibility check module 18 the information as to whether a target object has been selected and is being tracked.

Based on this information, the jam detection device 28 decides with the aid of an algorithm, which will be explained in more detail below in connection with Figure 2, whether the own vehicle is in a traffic jam situation or not. Accordingly, the jam detection device 28 transmits a logical jam signal

S, which assumes either the value "yes" or "no", to a presetting device 30, which specifies a number of control parameters for the controller 20.

These control parameters include a number of dynamic parameters, e.g. Determine how much the own vehicle can be accelerated or decelerated to keep the distance to the target object, and which acceleration curve is to apply for the automatic starting from a standing position. When a congestion is detected, these parameters are generally changed in the sense of less dynamic, that is, only the magnitude of smaller accelerations and delays are allowed, so that in dust operation a more comfortable and fuel-efficient driving is achieved. Alternatively, a parameter may be varied which determines at which distance and or which speed of the preceding vehicle an automatic starting process is initiated.

Another parameter concerns the output of acoustic, optical or haptic

Start-up instructions to the driver before initiating an automatic start-up procedure. For example, in the "normal" stop-and-go operation, when there is no congestion, it may be provided that a start-up instruction is output when the standstill time of the vehicle has exceeded a certain value, for example a few seconds. However, if the jam detection device 28 has detected a jam situation, be completely suppresses these starting instructions, so that the driver does not feel disturbed by the frequent occurrence of such instructions.

Another parameter in the example shown is the setpoint speed VSET, to which the controller 20 controls in free-ride mode. Usually this corresponds

Target speed of the desired speed selected by the driver. However, if a jam has been detected and the jam situation has persisted for some time, there is a risk that the driver has forgotten that a relatively high desired speed is still stored, and the driver could at resolution of the jam by the automatic acceleration to this high desired speed to be surprised. Therefore, it is useful under these conditions, the target speed to a certain value, for example, on motorways to reduce 60 or 80 km / h, so that the driver, if he wants to drive faster, by accelerator and / or switch operation actively a new desired speed must enter.

Finally, the traffic jam signal output by the recognition device 28 is also made available via an on-board CAN bus to other system components of the vehicle, for example the transmission control (not shown) or the navigation system 22 for calculating a route for bypassing the traffic jam.

The operation of the jam recognition device 28 will now be explained in more detail with reference to the diagram shown in FIG.

As long as the plausibility check module 18 reports that a target object is present, the speed V of the vehicle reported by the speed sensor 26 is continuously evaluated in the traffic jam recognition device 28. The curve 32 in Figure 2 shows a typical time course of the velocity V before, during and after a traffic jam.

The measured speed V is compared with an upper limit speed Vl. For example, this limit speed Vl may generally be 40 km / h, or it may vary depending on the type of road and on the traffic lane being traveled. For example, it may be 60 km / h on the left or middle lane of a highway, 40 km / h on the right lane of highways, and only 30 km / h in urban areas (with a general speed limit of 50 km / h). Before the time t1 in Figure 2, V is above V1, and nothing indicates a jam. However, as soon as V drops below Vl, the difference Vl-V is integrated over time. The time course of the integral P thus obtained is represented by the curve 34 in FIG. If at time t2, the velocity V is below a lower

Limit speed V2 decreases, which is for example 50% of VI, the integration is suspended, and the achieved value of the integral P is maintained. If the speed V increases again above V2, in the example shown at t3, then the integration is continued. The positive contributions to the integral P are also shown in FIG. 2 as ascending shaded areas 36, which are indicated by the curve 32 and the straight line V

= Vl be limited.

If at time t4 the velocity V rises again above V1, the integrand becomes negative and the integral P decreases again. The corresponding negative contribution to the integral P is represented by falling hatched areas 38.

The integral P can be interpreted as a congestion probability. As long as this congestion probability is below an upper threshold value Pl, the logical congestion signal S output by the congestion recognition device 28, represented in FIG. 2 by the curve 40, has the value "no".

In the example shown, the speed V temporarily has the value 0 in the interval between t2 and t3, that is, the vehicle has stood, for example in front of a red traffic light. However, since the integration is suspended below V2, this does not result in an increase in the integral P and the congestion probability remains smaller than Pl.

Thus, waiting in a traffic light queue is not mistakenly interpreted as a traffic jam.

In the example shown it is assumed that the vehicle approaches a jam end in the time interval between t4 and t5, so that the controller 20 causes a deceleration of the vehicle. At time t5, V again drops below V1, and the integrand becomes positive again.

It is characteristic of a traffic jam situation that the speed V remains below V1 for a longer time, so that the integral P finally reaches the upper threshold P1 at the time t6. This threshold Pl is chosen so that it will not be reached when the Vehicle stops only once in front of a red traffic light and thereby briefly (in the deceleration phase between tl and t2 and in the start-up phase between t3 and t4) passes the speed range between V1 and V2. Only after a long journey at a speed below V1 is the threshold value P1 reached and the traffic jam signal S changes to the state "yes". From the time t6 are thus by the

Default device 30, the control parameters adapted to the storage operation. In addition, from that point on the integration is suspended again, so that the integral P does not increase beyond the upper threshold Pl.

When the traffic jam dissolves again, the speed V increases again and at t7 exceeds the upper limit speed Vl. At this moment the integration is continued again, but the integrand is now negative, so that the congestion probability P decreases. If the velocity V now falls below Vl again (not shown in the drawing), then the integrand would become positive again, and the signal would increase again up to a maximum of P1. In the example shown remains the

However, speed V is greater than V1 and the integral P falls below a lower threshold P2 at time t8. This causes the jamming signal S to go back to the "no" state, that is, the system has detected the resolution of the jam and the control parameters are reset to normal.

However, integration continues even after time t8, until finally at time t9 the integral P has decreased to zero. Only then is the integration terminated, so that the state prevailing before the time tl is restored.

However, if in the time interval t8 and t9 the speed V again drops below Vl, then the integral P would immediately rise again from the value reached at that time, so that the upper threshold value Pl would be reached correspondingly faster. In that regard, between the times t8 and t9 a certain "memory" of the previous storage situation remains.

According to a modification (not shown), it is conceivable to reset the integral P to 0 (with which also S again assumes the value "no") as soon as the velocity V exceeds a velocity value V3, which is significantly greater than V1. Furthermore, while it has been assumed in the exemplary embodiment described above that the integral P is formed by integration of the speed difference V 1 -V, in an alternative embodiment it is also possible to simply count the time within which the speed V is above V 1 or V 1. between V1 and V2 lies. The integrand would then be: sgn (Vl-V), where sgn is the signum function, which has the value +1 if the argument is positive and -1 if the argument is negative.

Claims

claims

A vehicle distance and speed controller comprising a sensor system (12) for locating vehicles in front and a controller (20) which regulates the speed of the vehicle and / or the distance to a vehicle ahead based on predetermined control parameters, characterized by Stowage recognition device (28) and a default device (30) for adapting the control parameters to a detected congestion situation.

2. Distance and speed controller according to claim 1, characterized in that at least one of the control parameters is a dynamic parameter which characterizes the acceleration and / or deceleration behavior of the vehicle determined by the controller (20).

3. distance and speed controller according to claim 1 or 2, characterized in that at least one of the control parameters is a parameter that determines whether before a by the controller (20) automatically initiated starting a Hinfahrhinweis is issued to the driver, and that the Default device (30) is designed to block the output of the Anfahrhinweises in a traffic jam situation.

4. Distance and speed controller according to one of the preceding

Claims, characterized in that at least one of the control parameters is a target speed (VSET) for the speed control in the absence of a preceding vehicle and that the default means (30) is adapted after detection of a traffic jam situation or at least when the traffic jam situation persists for a certain time has to reduce the desired speed (VSET) from a desired speed selected by the driver to a lower speed.

5. Distance and speed controller according to one of the preceding

Claims, characterized in that the jam recognition device (30) has a Output (CAN) via which a jam signal (S) can also be output to other system components of the vehicle.

6. Distance and speed controller according to one of the preceding claims, characterized in that the traffic jam detection means (28) is adapted to decide that there is no congestion when the sensor system (12) locates no preceding vehicle, which is tracked as a target object.

7. distance and speed controller according to claim 6, characterized in that the jam detection means (28) is adapted to a

To calculate congestion probability (P) by time integration with a positive integrand when the vehicle speed (V) is below a predetermined upper limit speed (Vl) and a negative integrant when the vehicle speed (V) is above the predetermined upper limit Limit speed (Vl) is.

8. Distance and speed controller according to claim 7, characterized in that the jam detection means (28) is adapted to suspend the integration when the speed (V) of the vehicle is below a predetermined lower limit speed (V2), which is smaller than that upper

Limit speed (Vl).

9. distance and speed controller according to claim 7 or 8, characterized in that the congestion detection means (28) is adapted to limit the congestion probability (P) to a predetermined maximum value (Pl).

10. distance and speed controller according to one of claims 7 to 9, characterized in that the congestion detection means (28) is adapted to suspend the integration, as long as the congestion probability (P) is at least equal to an upper threshold value (Pl).

11. Distance and speed controller according to one of claims 7 to 10, characterized in that the jam detection means (28) is adapted to output a jam signal (S) when the congestion probability (P) an upper Threshold (Pl) reached, and the jam signal (S) to reset when the congestion probability (P) falls below a lower threshold (P2).

12. Distance and speed controller according to one of claims 7 to 12, characterized in that a device (24) is provided for classifying the road or road traveled by the vehicle and that the jam detection means (28) is adapted to at least one of the upper and lower limit speeds (V1, V2) and / or at least one of the upper and lower threshold values (P1, P2), depending on the road or road type.